For many years, it has been a common practice to attach refueling pods to certain military aircraft and to use such refueling pods for purposes of conducting inflight refueling operations. Currently-known refueling pods typically comprise a fuel storage area and an elongated hose which is adapted to be reeled in and reeled out from the refueling pod for purposes for providing a fuel supply line from the pod to the aircraft to be refueled. As can be appreciated, the refueling pod must necessarily include a reeling mechanism for reeling in and reeling out the fuel line as well as a pump for pumping fuel from the storage area into the fuel line.
It is well known in the prior art to provide a ram air turbine with the refueling pod for purposes of providing power to the fuel pump and to the reeling mechanism. Additionally, other prior art ram air turbines are used in conjunction with the reeling mechanisms of aerial targets. In this respect, the ram air turbine typically is used to provide power to the reeling mechanism to pay in and pay out the target from the aircraft.
Many of the prior art ram air turbines include variable pitch turbine blades associated therewith. In this respect, such turbines generally include mechanisms adapted to move the turbine blades to a feathered, i.e. non-rotating, position when a fuel pumping or reeling operation is not being conducted and to a power, i.e. rotating, position when power is needed to operate a pump or reeling mechanism. Though these prior art turbines have generally been suitable for most fuel pumping and reeling applications, such turbines possess certain deficiencies which detract from their overall utility. In this respect, the single greatest deficiency relates to the mechanisms used to adjust the turbine blades between the feathered and power positions to maintain desired operational speed.
In prior art ram air turbines, two different types of mechanisms are generally used to vary the turbine blade pitch. The first mechanism is a conventional clutch which is interfaced to both the turbine blades and output shaft of the turbine. The clutch is adapted to drive the turbine blades to a feathered orientation during non-usage and to move the turbine blades back to a power position when needed to operate a pump or reeling device. However, aerodynamic imperfections of the ram air turbine blades may produce a torque when in the feathered position which slowly rotates the clutch pressure plates comprising such clutch mechanisms tending to quickly wear them out and thus require continuous maintenance and expensive repair procedures to maintain the turbine in a properly functioning state.
The second most commonly used mechanism is a mechanical cam plate which is also operable to drive the turbine blades to the feathered or power positions for the previously described reasons. The cam plate however, must be mechanically driven by a bi-directional serve motor that is controlled with a feedback system which must monitor turbine rotational speed. This system is mechanically and electrically complex and a failure of the control system or servo motor could leave the turbine blades in a position that would result in excessive turbine rotational speed if the aircraft's airspeed is increased. The present invention alleviates these and other deficiencies associated with prior art ram art turbines.